Powder coating composition, coating film, and coated body

Abstract

Provided are: a powder coating composition which is capable of forming a coating film that has gloss and excellent flash properties, and which has excellent recyclability; and the like. This powder coating composition contains resin-containing powder particles (A), a flash pigment (B), and a binder (C), wherein the binder (C) is a resin having a Tg of 30 DEG C or more and a weight-average molecular weight of 1000-100,000, said binder (C) being dissolved or dispersed in a solvent (D) having an interaction distance Ra of 20 or more when the center coordinates ([delta] d, [delta] p, [delta] h) in Hansen dissolved balls (HSS) for discriminating the solubility of the mixed solvent are set to be (19.0, 7.0, 5.0).

Description

Technical Field

[0001] The present invention relates to a powder coating composition, a coating film and a coated body. Background Art

[0002] Currently, thermosetting powder coatings containing fluororesins, non-fluororesins, and pigments are known as powder coatings that exhibit weather resistance and good adhesion to substrates. Using a shimmering pigment as a pigment in such powder coatings can form a coating film with shimmering properties (see, for example, Patent Document 1). Electrostatic powder coating is one method used to form the coating film.

[0003] However, the charge rates of the resin powder and luster pigments (such as metallic pigments) that make up powder coatings generally differ significantly. Consequently, when electrostatic powder coating is performed using powder coatings containing both resin powder and luster pigment, separation between the resin powder and luster pigment is likely to occur during application. This separation can degrade the appearance of the resulting coating film. Furthermore, this separation can easily cause the pigment content of the powder coating to vary between before and after application. This variation in pigment content can easily lead to a change in color tone between a coating film obtained using recycled and reused powder coatings and a coating film obtained using unrecycled powder coatings, making the recycling (reuse) of powder coatings difficult.

[0004] Various proposals have been proposed. For example, Patent Documents 2 and 3 disclose methods for attaching the glitter pigment to the surface of the thermosetting resin powder using a tacky binder (a bonding method) to prevent separation between the thermosetting resin powder and the metallic pigment. Furthermore, the examples of Patent Documents 2 and 3 disclose the use of a terpene-based resin as a binder.

[0005] Furthermore, Patent Document 4 discloses a method for bonding resin powders, particularly fluororesin powders. Specifically, Patent Document 4 discloses a powder coating containing resin powders comprising fluororesin and non-fluororesin, a glittering pigment, and a binder, and a method for bonding the glittering pigment to the surface of thermosetting resin powder using a binder composed of a surfactant with a melting point of 25°C or higher. The examples in Patent Document 4 disclose the use of a fluorine-based halogenated solvent as the solvent for the binder.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-12119

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-175813

[0010] Patent Document 3: Japanese Patent No. 3926270

[0011] Patent Document 4: Japanese Patent No. 6841235 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] When using the terpene-based resins used in the examples of Patent Documents 2 and 3 as adhesives, the terpene-based resins must be dissolved in a low-polarity solvent such as n-heptane. However, since these low-polarity solvents generally dissolve fluororesins, they can easily cause problems when used with thermosetting resin powder particles containing fluororesins. Specifically, when these low-polarity solvents are used with thermosetting resin powder particles containing fluororesins, the fluororesins partially dissolve, causing the thermosetting resin powder particles to stick together. This can lead to an increase in the particle size of the thermosetting resin powder, a decrease in coating workability, or a deterioration in the appearance of the coating film.

[0014] Furthermore, the fluorine-based halogen-containing solvents used in the examples of Patent Document 4 generally dissolve fluororesins. Therefore, similar to the use of low-polarity solvents in Patent Documents 2 and 3, the use of these fluorine-based halogen-containing solvents in thermosetting resin powder particles containing fluororesins may increase the particle size of the thermosetting resin powder, reduce coating workability, or deteriorate the appearance of the coating film.

[0015] Furthermore, when the powder coating material contains a resin having a carboxyl group, there is also a problem that the glossiness of the coating film tends to decrease when the binders disclosed in Patent Documents 2 to 4 are used.

[0016] A powder coating composition containing resin-containing powder particles, a glitter pigment, and a binder for use in bonding methods desirably contains a solvent that dissolves the binder but does not dissolve the resin of the resin-containing powder particles. In contrast, the powder coating compositions disclosed in Patent Documents 2 to 4 are only applicable to bonding methods when using specific resin and binder compositions. In the art, powder coating compositions are expected to be widely applicable to various bonding methods for resin-containing powder particles, given the design flexibility they offer.

[0017] The present invention has been made in response to the above-mentioned problems, and its object is to provide a powder coating composition that can form a coating film having a glossy and excellent glittering property and that also has excellent recyclability. Furthermore, the present invention aims to provide a coating film and a coated article formed using the powder coating composition.

[0018] Solutions for solving problems

[0019] The present inventors have successfully developed a powder coating composition and finally completed the present invention. The powder coating composition contains resin powder particles, glitter pigment and binder, wherein the Hansen solubility parameter (HSP) (δ d , δ p , δ h ) forms a specific Hansen's dissolving sphere, and the binder is dissolved or dispersed at a distance relative to the center coordinate of the specific Hansen's dissolving sphere, that is, the interaction distance R a When the solvent content of the resin is 20 or more, a coating film having gloss and excellent glitter can be formed, and furthermore, the recyclability is also excellent.

[0020] (1) The powder coating composition of the present invention comprises resin-containing powder particles (A), a luster pigment (B), and a binder (C), wherein the binder (C) is dissolved or dispersed in a Hansen Solving Sphere (HSS) for determining solubility in a mixed solvent. d , δ p , δ h ) is set to (19.0, 7.0, 5.0) a A resin having a Tg of 30° C. or higher and a weight average molecular weight of 1,000 to 100,000 in a solvent (D) of 20 or higher.

[0021] (2) Preferably, the binder (C) is dissolved or dispersed in the interaction distance R a The resin of the solvent (D) is 30 or more.

[0022] (3) Preferably, the Tg of the binder (C) is 40°C or higher.

[0023] (4) Preferably, the resin (A1) constituting the resin-containing powder particles (A) is a resin obtained by reacting one or more binder resins (A11) selected from the group consisting of fluororesins, polyester resins, and acrylic resins, with one or more curing agents (A12) selected from the group consisting of compounds having an epoxy group or polymers thereof, amide compounds, and isocyanate compounds.

[0024] (5) Preferably, the solvent (D) is one or more solvents selected from the group consisting of water, ethylene glycol, and methanol.

[0025] (6) Preferably, the solvent (D) is a mixed solvent of water and a water-soluble organic solvent.

[0026] (7) Preferably, the shimmering pigment (B) is a flaky aluminum sheet.

[0027] (8) The coating film according to the present invention is formed using the powder coating composition.

[0028] (9) The coated body according to the present invention comprises: a substrate; and a coating film formed on the surface of the substrate using the powder coating composition.

[0029] Effects of the Invention

[0030] The present invention provides a powder coating composition that can form a coating film having a glossy and excellent glittering property and is also highly recyclable. Furthermore, the present invention provides a coating film formed using the powder coating composition and a coated article having the coating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is used to use HSP (δ d , δ p , δ h ) A diagram illustrating a method for creating a Hansen's dissolving sphere having specific center coordinates and a specific interaction radius R0 on a Hansen's 3D chart;

[0032] Figure 2 Graph showing a solvent group that dissolves a resin (virtual resin X) for forming a specific Hansen sphere and a solvent group that does not dissolve the resin (virtual resin X);

[0033] Figure 3 is a solvent group that dissolves the resin (virtual resin X) used to form a specific Hansen dissolving sphere, a solvent group that does not dissolve the resin (virtual resin X), and a solvent group located at an interaction distance R from the center coordinate (CC) of the specific Hansen dissolving sphere. a Diagram of the location of the solvent. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. For convenience of description, the shapes and sizes of the drawings have been appropriately modified. Therefore, the present invention is not limited to the shapes of the drawings.

[0035] [Powder coating composition]

[0036] The powder coating composition according to the present invention contains resin-containing powder particles (A), a bright pigment (B), and a binder (C).

[0037] (Contains resin powder particles (A))

[0038] The resin-containing powder particles (A) contain at least a resin (A1). The resin (A1) contains at least a binder resin (A11) and, if necessary, may further contain a curing agent (A12). The curing agent (A12) is a compound or polymer that reacts with the binder resin (A11). The curing agent (A12) preferably does not react during the preparation of the resin-containing powder particles (A) but reacts during film formation using the powder coating composition.

[0039] The resin-containing powder particles (A) are prepared, for example, by melt-kneading a mixture containing at least a binder resin (A11) and, if necessary, a curing agent (A12), followed by cooling and pulverization, so as to contain the resin (A1). Furthermore, the mixture may further contain additives (A2) such as a surface conditioner and a lubricant, and a coloring pigment (A3), as needed.

[0040] When the mixture further contains an additive (A2), the resulting resin-containing powder particles (A) contain the resin (A1) and a component derived from the additive (A2). Here, "component derived from the additive (A2)" refers to the additive (A2) itself or a reaction product between the additive (A2) and another component.

[0041] Moreover, when the said mixture further contains a coloring pigment (A3), the obtained resin-containing powder particle (A) contains the resin (A1) and the coloring pigment (A3).

[0042] Furthermore, when the additive (A2) and the color pigment (A3) are further contained, the obtained resin-containing powder particles (A) contain the resin (A1), a component derived from the additive (A2), and the color pigment (A3).

[0043] <Binder resin (A11)>

[0044] As the binder resin (A11), for example, one or more selected from the group consisting of fluororesins, polyester resins, and acrylic resins may be used, and a plurality of binders may be combined and prepared.

[0045] The fluororesin used for the binder resin (A11) is a fluorinated copolymer obtained by polymerizing or copolymerizing a fluorinated monomer.

[0046] As the fluororesin, for example, a resin that is solid at room temperature and has a softening point of 50 to 150°C is used.

[0047] Examples of the fluorine-containing monomer include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and (per)fluoroalkyl trifluorovinyl ether [the (per)fluoroalkyl group has 1 to 18 carbon atoms].

[0048] Fluororesins may be obtained by copolymerizing a fluorine-containing monomer with a polymerizable monomer other than the fluorine-containing monomer. Examples of the polymerizable monomer include vinyl ethers, olefins, allyl ethers, vinyl esters, allyl esters, (meth)acrylates, and crotonates.

[0049] Examples of the polymerizable monomer include:

[0050] Alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, and chloroethyl vinyl ether;

[0051] Olefins such as ethylene, propylene, 1-butene, isobutylene, cyclohexene, vinyl chloride, and vinylidene chloride;

[0052] Styrene monomers such as styrene and α-methylstyrene;

[0053] Alkyl allyl ethers such as methyl allyl ether, ethyl allyl ether, butyl allyl ether, and cyclohexyl allyl ether;

[0054] Fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl hexanoate, vinyl octanoate, and vinyl versatate;

[0055] Fatty acid allyl esters such as allyl propionate and allyl acetate;

[0056] (Meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate;

[0057] (Meth)acrylamide and other (meth)acrylamides; acrylonitrile, 2,4-dicyanobutene-1 and other cyano group-containing monomers;

[0058] Polymerizable monomers such as dienes such as isoprene and butadiene.

[0059] The fluororesin may have a reactive site that reacts with a curing agent, etc. Alternatively, the fluororesin may be a copolymer of one or more of the above-mentioned fluorine-containing monomers and polymerizable monomers and a reactive group-containing monomer.

[0060] As the reactive group-containing monomer, a monomer containing a functional group such as a hydroxyl group, a carboxyl group, an amide group, an amino group, a nitrile group, a glycidyl group, or an isocyanate group is used. As the reactive group-containing monomer, for example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an amide group-containing monomer, a nitrile group-containing monomer, a glycidyl group-containing monomer, or an isocyanate group-containing monomer is used.

[0061] Examples of the hydroxyl group-containing monomer include:

[0062] Allyl alcohol;

[0063] Hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 4-hydroxycyclohexyl vinyl ether;

[0064] Hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, 3-hydroxypropyl allyl ether, 4-hydroxybutyl allyl ether, and 4-hydroxycyclohexyl allyl ether;

[0065] Hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate;

[0066] Esters of hydroxyalkyl carboxylic acids and vinyl alcohol, such as vinyl glycolate, vinyl hydroxyisobutyrate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, and vinyl hydroxycyclohexylcarboxylate;

[0067] Hydroxyalkyl allyl esters such as hydroxyethyl allyl ester, hydroxypropyl allyl ester, hydroxybutyl allyl ester, and hydroxyisobutyl allyl ester.

[0068] In addition, carboxyl group-containing monomers include (meth)acrylic acid and carboxyl alkyl allyl esters. Amino group-containing monomers include aminoalkyl vinyl ethers and aminoalkyl allyl ethers. Amide group-containing monomers include (meth)acrylamide and N-methyl (meth)acrylamide. Nitrile group-containing monomers include (meth)acrylonitrile. Glycidyl group-containing monomers include glycidyl allyl ether and glycidyl (meth)acrylate. Isocyanate group-containing monomers include vinyl isocyanate and isocyanate ethyl acrylate.

[0069] The fluorine content of the fluororesin used in the present invention is preferably 10 to 70% by mass.

[0070] When a substance reactive with a hydroxy group is used as the curing agent component (A12), the hydroxy value of the fluororesin is preferably 10 to 100 mgKOH / g, more preferably 30 to 70 mgKOH / g.

[0071] When a substance reactive with a carboxyl group is used as the curing agent component (A12), the acid value of the fluororesin is preferably 1 to 80 mgKOH / g, more preferably 10 to 60 mgKOH / g.

[0072] The polyester resin used in the binder resin (A11) is obtained by reacting a carboxylic acid with a polyol by a known method and is a solid resin at room temperature. The softening point of the polyester resin is preferably 100 to 150°C.

[0073] Examples of the carboxylic acid component containing carboxylic acid include polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,2-octadecanedicarboxylic acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, trimellitic acid, and pyromellitic acid; lower alkyl esters of these polycarboxylic acids and their anhydrides; and hydroxycarboxylic acids such as malic acid, tartaric acid, 1,2-hydroxystearic acid, and p-hydroxybenzoic acid.

[0074] Examples of the polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, spiroglycol, 1,4-cyclohexanedimethanol, trimethylolethane, trimethylolpropane, glycerol, and pentaerythritol.

[0075] The polyester resin can be produced using the aforementioned carboxylic acid component and polyol as raw materials using conventional methods for producing polyester resins for powder coatings. For example, the various raw materials described above can be used in appropriate combinations and proportions, followed by an esterification or transesterification reaction at 200-280°C according to conventional methods, followed by a polycondensation reaction at 230-290°C under reduced pressure using a catalyst, and then a depolymerization reaction using an alcohol component to produce the polyester resin.

[0076] The polyester resin preferably has a number average molecular weight of 8,000 or less and a weight average molecular weight of 10,000 to 20,000 from the viewpoint of controlling the melt viscosity.

[0077] When a substance reactive with a hydroxy group is used as the curing agent component (A12), the hydroxy value of the polyester resin is preferably 20 to 100 mgKOH / g, more preferably 30 to 80 mgKOH / g.

[0078] When a substance reactive with a carboxyl group is used as the curing agent component (A12), the acid value of the polyester resin is preferably 1 to 80 mgKOH / g, more preferably 10 to 60 mgKOH / g.

[0079] Furthermore, for powder coatings containing fluororesins and polyester resins, if the melt viscosity of the polyester resin used is 3.5 Pa·s or less at 190°C and the slope of an Arrhenius plot of temperature and viscosity between 100°C and 120°C, measured using a rheometer at a cooling rate of 10°C / minute from 200°C, is 15,000 or greater, the fluororesin component tends to concentrate on the surface of the coating during film formation. This concentration of the fluororesin component on the surface of the coating improves the weather resistance of the coating.

[0080] The above-mentioned slope is calculated, for example, by the following method. First, the viscosity is measured using a TA Instruments rheometer, ARES, under the following measurement conditions: parallel plates with a diameter of 40 mm, a gap width of 1.0 mm, a frequency of 9.42 rad / s, and a strain of 1.0%. Next, a graph (Arrhenius plot) is created using the measurement results, with the horizontal axis plotting the inverse of the temperature (T) (Kelvin) (1 / T) and the vertical axis plotting the logarithm of the viscosity (V) (lnV). The slope of the resulting straight line at 100-120°C is then calculated, and this value is used as the above-mentioned slope.

[0081] From the viewpoint of facilitating layer separation of the coating film, the slope is more preferably 16,000 to 20,000.

[0082] The acrylic resin used in the binder resin (A11) is a solid resin at room temperature and is a polymer of acrylic acid esters or methacrylic acid esters. Examples of the acrylic resin include polymers obtained by polymerizing one or more acrylic components selected from acrylic acid, methacrylic acid, and their esters, amides, and nitriles. Alternatively, polymers obtained by polymerizing an acrylic component and a non-acrylic component such as styrene may be used. For the purpose of controlling melt viscosity, the acrylic resin preferably has a softening point of 100 to 150°C, a number average molecular weight of 8,000 or less, and a weight average molecular weight of 10,000 to 20,000.

[0083] Examples of the acrylic acid component include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonanoic (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and octyl (meth)acrylate. (Meth)acrylate monomers such as phenyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, and ethoxypropyl (meth)acrylate; and functional group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, 2-aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 2-butylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, and allyl glycidyl ether. In addition, as the acrylic component, acrylic acid or methacrylic acid; amide monomers such as acrylamide and methacrylamide; alkoxysilyl group-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth)acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, and γ-(meth)acryloxypropyldiethylmethoxysilane may be used.

[0084] The ratio of the acrylic component to the entire components constituting the acrylic resin is, for example, 40 to 100% by mass.

[0085] As non-acrylic components, for example: carboxyl group-containing monomers such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinyl versatate; aromatic monomers such as styrene, methylstyrene, chlorostyrene, methoxystyrene, and vinyltoluene; olefin monomers such as ethylene and propylene; vinyl monomers such as vinyl acetate and vinyl chloride; amide monomers such as maleic acid amide; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; dialkyl fumarate, allyl alcohol, vinylpyridine, butadiene, etc.

[0086] When a substance reactive with a hydroxyl group is used as the curing agent component (A12), the hydroxyl value of the acrylic resin is preferably 20 to 100 mgKOH / g, more preferably 30 to 80 mgKOH / g.

[0087] When a substance reactive with a carboxyl group is used as the curing agent component (A12), the acid value of the acrylic resin is preferably 1 to 80 mgKOH / g, more preferably 10 to 60 mgKOH / g.

[0088] Curing agent (A12)

[0089] As the curing agent (A12), one or more selected from the group consisting of a compound having an epoxy group or a polymer thereof, an amide compound, and an isocyanate compound is used.

[0090] As the compound having an epoxy group, a compound having a plurality of epoxy groups in the molecule is preferred, and triglycidyl isocyanurate is a representative example.

[0091] Examples of polymers having epoxy groups (hereinafter also referred to as epoxy resins) include bisphenol-type epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin, naphthalene epoxy resins, biphenyl epoxy resins, novolac epoxy resins, cycloaliphatic epoxy resins, glycidylamine resins, heterocyclic epoxy resins, and polyfunctional epoxy resins. These can be used alone or in combination.

[0092] Examples of the epoxy resin include solid epoxy resins synthesized from bisphenol A and epihalohydrin such as epichlorohydrin, and solid epoxy resins obtained by an extension reaction of bisphenol A, epoxy resins derived from dihydric phenols and epihalohydrin, and bisphenol A.

[0093] Commercially available epoxy resins include jER1004, jER1004F, jER1007, and jER4005P manufactured by Mitsubishi Chemical Corporation, EPICLON 3050 and EPICLON 4050 manufactured by DIC Corporation, EPOTOH TOY D014D manufactured by Nippon Steel & Sumikin Chemical Corporation, and EPONANYANPES-904 manufactured by Nanya Plastics Co., Ltd.

[0094] The softening point of the epoxy resin is not particularly limited, but is preferably 60 to 150° C. The epoxy equivalent of the epoxy resin is also not particularly limited, but is preferably 400 to 3,000.

[0095] As the epoxy resin, a plurality of epoxy resins having different epoxy equivalents may be mixed and used. When a plurality of epoxy resins are mixed, it is preferable to combine an epoxy resin having an epoxy equivalent of 1000 or less with an epoxy resin having an epoxy equivalent of 1000 or more.

[0096] The epoxy resin has a difference in epoxy equivalent between the epoxy resin having the smallest epoxy equivalent (A-min) and the epoxy resin having the largest epoxy equivalent (A-max) of usually 300 or more, preferably 500 or more, and more preferably 800 or more.

[0097] As the amide compound, for example, β-hydroxyalkylamide is used. From the perspective of low-temperature curability and water resistance of the resulting coating film, the β-hydroxyalkylamide preferably has two or more functional groups per molecule. From the perspective of low-temperature curability and water resistance of the resulting coating film, the β-hydroxyalkylamide is more preferably N,N-bis(β-hydroxyethyl)acetamide, bis(β-hydroxyethyl)adipamide, bis(β-hydroxypropyl)adipamide, bis[N,N-bis(β-hydroxyethyl)]adipamide, or bis[N,N-bis(β-hydroxypropyl)]adipamide. The equivalent weight of the hydroxyamide groups in the β-hydroxyalkylamide relative to the carboxyl groups in the resin is preferably 0.5 to 1.5 equivalents.

[0098] As the isocyanate compound, for example, a blocked isocyanate compound is used. It is preferable to use a compound that is solid at room temperature.

[0099] The blocked isocyanate compound can be produced by, for example, reacting an aliphatic, aromatic, or aromatic aliphatic diisocyanate with a low-molecular compound having active hydrogen, and reacting the resulting polyisocyanate with a blocking agent to perform masking. Therefore, the blocked isocyanate compound can be easily produced.

[0100] Examples of the diisocyanate include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylenediisocyanate, hexamethylene diisocyanate, 4,4′-methylenebis(cyclohexylisocyanate), methylcyclohexane diisocyanate, bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, and lysine diisocyanate.

[0101] As low molecular weight compounds having active hydrogen, water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, methanolamine, dimethanolamine, hexamethylenediamine, etc., as well as isocyanurate, uretdione, hydroxyl group-containing low molecular weight polyester, polycaprolactone, etc. are used.

[0102] As the blocking agent, alcohols such as methanol, ethanol, and benzyl alcohol; phenols such as phenol and crezone; lactams such as caprolactam and butyrolactam; oximes such as cyclohexanone, oxime, and methyl ethyl ketoxime are used.

[0103] For example, as a specific example of the blocked isocyanate, isophorone diisocyanate blocked with ε-caprolactam (Vestagon B1530 manufactured by Evonik, Crelan UI manufactured by Bayer AG) and the like are used.

[0104] The softening point of the isocyanate compound is preferably 10 to 120°C, more preferably 40 to 100°C. If the softening point is lower than 10°C, the powder coating composition may solidify or form granular masses at room temperature. On the other hand, if the softening point exceeds 120°C, it may be difficult to uniformly disperse the isocyanate compound in the powder coating composition during melt kneading, which may impair the smoothness, coating strength, moisture resistance, and other properties of the resulting coating film.

[0105] As an isocyanate compound, the equivalent of the isocyanate group relative to the hydroxyl group in the resin is preferably 0.05 to 1.5 equivalents, and more preferably 0.8 to 1.2 equivalents. If the isocyanate group is less than 0.05 equivalents, the degree of curing of the powder coating composition may be insufficient, and the coating properties such as adhesion, coating hardness, and chemical resistance may be reduced. In addition, if the isocyanate group exceeds 1.5 equivalents, the coating may become brittle or its heat resistance, chemical resistance, moisture resistance, etc. may deteriorate. In addition, since blocked isocyanates are expensive, excessive use of blocked isocyanates can easily increase costs.

[0106] The resin (A1) constituting the resin-containing powder particles (A) preferably comprises one or more binder resins (A11) selected from the group consisting of fluororesins, polyester resins, and acrylic resins, and one or more curing agents (A12) selected from the group consisting of compounds having an epoxy group or polymers thereof, amide compounds, and isocyanate compounds.

[0107] The resin (A1) constituting the resin-containing powder particles (A) more preferably contains at least one binder resin (A11) selected from the group consisting of fluororesins and polyester resins, and a curing agent (A12) composed of an isocyanate compound.

[0108] The resin (A1) constituting the resin-containing powder particles (A) more preferably includes a binder resin (A11) composed of a polyester resin and a curing agent (A12) composed of a compound having an epoxy group or a polymer thereof.

[0109] The resin (A1) constituting the resin-containing powder particles (A) more preferably contains a binder resin (A11) composed of a polyester resin and a curing agent (A12) composed of an amide compound.

[0110] Additives (A3)

[0111] Examples of the additives (A3) include plasticizers, curing accelerators, crosslinking catalysts, surface conditioners, ultraviolet absorbers, light stabilizers, antioxidants, flow control agents, anti-sagging agents, and defoaming agents, which are additives commonly used in coatings.

[0112] Coloring Pigments (A4)

[0113] As the coloring pigment (A4), for example, inorganic pigments such as titanium oxide, yellow iron oxide, titanium yellow, iron oxide red (iron oxide red), lithopone, and antimony oxide; and organic pigments such as Hansa Yellow 5G, Permanent Yellow FGL, Phthalocyanine Blue, Indanthrene Blue RS, Permanent Red F5RK, and Fast Scarlet G are used.

[0114] As described above, the resin-containing powder particles (A) are produced so as to contain the resin (A1) by, for example, melt-kneading a mixture containing at least the binder resin (A11) and the curing agent (A12), cooling and pulverizing the mixture.

[0115] The resin-containing powder particles (A) may contain, in addition to the resin (A1), a component derived from the additive (A2), a coloring pigment (A3), and the like, as necessary.

[0116] The 50% volume average particle size of the resin-containing powder particles (A) is, for example, 15 to 100 μm, preferably 20 to 70 μm, and more preferably 30 to 50 μm.

[0117] (Glitter paint (B))

[0118] Examples of the glittering pigment (B) include aluminum powder pigments, nickel powder pigments, stainless steel powder pigments, copper powder, bronze powder, gold powder, silver powder, mica pigments, graphite pigments, glass flake pigments, flaked plastic pigments, and flaky iron oxide pigments. Examples of the aluminum powder pigment include flaky aluminum flakes. Flaky aluminum flakes are preferred for the glittering pigment (B) due to their high glitter properties.

[0119] The 50% volume average particle size of the bright pigment (B) is, for example, 3 to 100 μm, preferably 5 to 80 μm, and more preferably 15 to 60 μm.

[0120] The aspect ratio of the luster pigment (B) is, for example, 2 to 60, preferably 3 to 40, and more preferably 5 to 25.

[0121] (Binder (C))

[0122] The binder (C) is a resin that binds (adheres) the resin-containing powder particles (A) and the luster pigment (B). The binder (C) is dissolved or dispersed in the solvent (D) to provide fluidity when binding (adhering) the resin-containing powder particles (A) and the luster pigment (B).

[0123] The binder (C) constituting the powder coating composition of the present invention is used together with a solvent (D) that does not dissolve the resin (A1) constituting the resin-containing powder particles (A) but dissolves or disperses the binder (C) when binding (adhering) the resin-containing powder particles (A) and the luster pigment (B).

[0124] Specifically, the binder (C) is a resin having a Tg and a weight average molecular weight within a specific range and is dissolved or dispersed in a solvent (D). The solvent (D) is at a specific center coordinate (δ) of the Hansen dissolution sphere on the Hansen 3D diagram. d , δ p , δ h ) = (19.0, 7.0, 5.0) is the interaction distance R a within a specific range.

[0125] More specifically, the binder (C) is dissolved or dispersed at the center coordinate (δ d , δ p , δ h ) is set to (19.0, 7.0, 5.0) a A resin having a Tg of 30° C. or higher and a weight average molecular weight of 1,000 to 100,000 in a solvent (D) having a molecular weight of 20 or higher.

[0126] The above Hansen's 3D diagram, Hansen dissolving sphere, center coordinates (δ d, δ p , δ h ) and interaction distance R a Based on HSP (δ d , δ p , δ h ) is formed and calculated. These concepts are explained below with reference to the accompanying drawings.

[0127] Hansen Solubility Parameter (HSP)

[0128] Figure 1 is used to use HSP (δ d , δ p , δ h ) A diagram illustrating a method for creating a Hansen's dissolving sphere with specific center coordinates and a specific interaction radius R0 on a Hansen's 3D chart.

[0129] Hansen HSP (δ d , δ p , δ h ) is a parameter defined by the following formula (1).

[0130] [Number 1]

[0131]

[0132] (δ: Hildebrand solubility parameter (SP) of substance X [KJ / cm 3 ] 1 / 2 , ΔE V : molar evaporation energy of substance X [KJ / mol], V: molar molecular volume of substance X [cm 3 / mol], ΔE d V : Molar evaporation energy of the dispersion force of substance X [KJ / mol], ΔE p V : Molar evaporation energy of the dipole-dipole force of substance X [KJ / mol], ΔE h V : Molar evaporation energy of hydrogen bonding of substance X [KJ / mol], δ d : the dispersion force term of the HSP of substance X, δ p : Dipole-dipole force term of HSP of substance X, δ h : hydrogen bond force term of HSP of substance X)

[0133] In the present invention, a virtual resin X is set as a resin that can be used as the substance X in the plurality of resins (A1) constituting the resin-containing powder particles (A). Specifically, in the present invention, the virtual resin X is set to a specific center coordinate (δ d , δ p , δ h ) = (19.0, 7.0, 5.0) of the resin. In the present invention, as the center coordinate of the Hansen dissolving sphere, a specific center coordinate (δ d , δ p , δ h ) = (19.0, 7.0, 5.0), so it is possible to bond glitter pigments to various resin-containing powder particles.

[0134] like Figure 1 As shown, HSP (δ d , δ p , δ h ) in the presence of δ d Axis, δ p Axis and δ h The three axes are represented on Hansen's 3D diagram G. On Hansen's 3D diagram G, HSP (δ d , δ p , δ h )by Figure 1 The point XC represents.

[0135] In the present invention, as Figure 1 The point XC (δ d , δ p , δ h ) is as described above, using the virtual resin X (δ d , δ p , δ h ) = (19.0, 7.0, 5.0), the (δ d , δ p , δ h ) = (19.0, 7.0, 5.0) are set as the center coordinates CC of the Hansen solution sphere HSS.

[0136] In the present invention, the (δ d , δ p , δ h ) = (19.0, 7.0, 5.0) as the center coordinates CC, and a Hansen Solving Sphere (HSS) is created. The Hansen Solving Sphere (HSS) is the smallest sphere containing only the solvent that dissolves the virtual resin X. The smallest sphere is calculated as the smallest sphere containing only the solvent that dissolves the virtual resin X when testing or simulating whether the virtual resin X dissolves in various solvents.

[0137] The radius of the Hansen dissolving sphere HSS is defined as the interaction radius R0. The interaction radius R0 is defined by the following formula (2) and is the distance from the center coordinate CC on the Hansen 3D graph G, that is, the interaction distance R a The Hansen Solving Sphere (HSS) contains only the radius of the smallest sphere of the solvent that dissolves the virtual resin X. Furthermore, in the following formula (2), component 1 is the virtual resin X, and component 2 is the solvent. In the present invention, based on the results of the aforementioned "tests or simulations of whether the virtual resin X dissolves with various solvents," it was discovered that the interaction radius R0 of the virtual resin X can be set to less than 20 (excluding 0).

[0138] [Number 2]

[0139]

[0140] (R a : interaction distance, δ d,1 : Dispersion term of HSP of component 1 (virtual resin X), δ d,2 : The dispersion force term of the HSP of component 2 (solvent), δ p,1 : Dipole-dipole force term of HSP of component 1 (virtual resin X), δ p,2 : Dipole-dipole force term of HSP of component 2 (solvent), δ h,1 : Hydrogen bond force term of HSP of component 1 (virtual resin X), δ h,2 : Hydrogen bonding force term of HSP of component 2 (solvent)

[0141] In general, Δδ defined in the following formula (3), that is, the solubility parameter HSP (δ d,1 , δ p,1 , δ h,1 ) and the HSP (δ d,2 , δ p,2 , δ h,2 The distance Δδ between the two components (component 1 (virtual resin X) and component 2 (solvent) is an indicator of their solubility. The smaller the Δδ, the more easily the two components dissolve, while the larger the Δδ, the less easily the two components dissolve.

[0142] [Number 3]

[0143]

[0144] (Δδ: Solubility parameter HSP (δ) of component 1 (virtual resin X) on Hansen's 3D chart G d,1 , δ p,1 , δ h,1) and the HSP (δ d,2 , δ p,2 , δ h,2 ) distance, δ d,1 : Dispersion term of HSP of component 1 (virtual resin X), δ d,2 : The dispersion force term of the HSP of component 2 (solvent), δ p,1 : Dipole-dipole force term of HSP of component 1 (virtual resin X), δ p,2 : Dipole-dipole force term of HSP of component 2 (solvent), δ h,1 : Hydrogen bond force term of HSP of component 1 (virtual resin X), δ h,2 : Hydrogen bonding force term of HSP of component 2 (solvent)

[0145] Figure 2 This is a diagram showing a solvent group that dissolves a resin (virtual resin X) for forming a specific Hansen sphere and a solvent group that does not dissolve the resin (virtual resin X).

[0146] exist Figure 2 In the figure, the solvent marked with "○ (white circle)" is located within the Hansen solubility sphere HSS with the center coordinate CC and the interaction radius R0, and dissolves the virtual resin X. On the other hand, the solvent marked with "□ (white square)" is located outside the Hansen solubility sphere HSS and does not dissolve the virtual resin X.

[0147] Figure 3 is a solvent group that dissolves the resin (virtual resin X) used to form a specific Hansen dissolving sphere, a solvent group that does not dissolve the above resin (virtual resin X), and a solvent group located at an interaction distance R from the center coordinate CC of the specific Hansen dissolving sphere. a Diagram of the location of the solvent.

[0148] exist Figure 3 In the figure, the solvent marked with ○ is located within the Hansen dissolution sphere HSS with the center coordinate CC and the interaction radius R0, and dissolves the virtual resin X. In addition, the solvent marked with □ is located outside the above-mentioned Hansen dissolution sphere HSS and does not dissolve the virtual resin X. Moreover, among the solvents marked with □, the solvent marked with DD is located outside the Hansen dissolution sphere HSS. Moreover, due to the interaction distance R a It is much larger than the interaction radius R0, so it can be said that the virtual resin X cannot be reliably dissolved.

[0149] The binder (C) is dissolved or dispersed at the interaction distance R a The solvent (D) is 20 or more, and the interaction distance R is preferably a The solvent (D) is 25 or more, and the interaction distance R is more preferably aThe resin in the solvent (D) is 30 or more. The solvent (D) will be described later.

[0150] The Tg of the binder (C) is 30°C or higher, preferably 40°C or higher, and more preferably 45°C or higher. If the Tg is lower than 30°C, the binder will still exhibit adhesiveness after the solvent evaporates, so sufficient adhesion between the resin-containing powder particles and the bright pigment cannot be achieved. In addition, the binder remaining on the surface of the powder particles causes the resin-containing powder particles (A) to adhere to each other, increasing the particle size of the resin-containing powder particles (A).

[0151] The weight-average molecular weight of the binder (C) is 1,000 to 100,000, preferably 2,000 to 70,000. More preferably, it is 2,000 to 50,000. If the weight-average molecular weight of the binder (C) is less than 1,000, sufficient adhesion between the resin-containing powder particles and the luster pigment may be difficult to achieve. If the weight-average molecular weight of the binder (C) exceeds 100,000, its solubility or dispersibility in solvents tends to deteriorate. Furthermore, the use of an emulsifier or dispersant can improve the dispersibility of the binder, but in this case, the adhesion between the resin-containing powder particles and the luster pigment tends to decrease.

[0152] (Solvent (D))

[0153] The solvent (D) is a solvent that dissolves or disperses the binder (C). For example, one or more solvents selected from the group consisting of water, ethylene glycol, and methanol are used as the solvent (D). A mixed solvent of water and a water-soluble organic solvent is preferred because this solvent (D) sufficiently maintains its insolubility in the resin-containing powder particles and facilitates wetting of the binder on the surfaces of the resin-containing powder particles.

[0154] (effect)

[0155] In the powder coating composition of the present invention, a solution or dispersion in which a binder (C) is dissolved or dispersed in a solvent (D) is prepared in advance, the resulting solution or dispersion is added to the resin-containing powder particles (A) and thoroughly mixed, and then the solvent (D) is completely volatilized. This allows the resin-containing powder particles (A) and the bright pigment (B) to be bonded (adhered) with the binder (C).

[0156] Here, examples of the method of “adding a solution or dispersion in which the binder (C) is dissolved or dispersed in the solvent (D) to the resin-containing powder particles (A) and thoroughly mixing them” include: “adding dropwise a solution or dispersion in which the binder (C) is dissolved or dispersed in the solvent (D) little by little at a specific rate while stirring the resin-containing powder particles (A)” and “a method of atomizing and spraying a solution or dispersion in which the binder (C) is dissolved or dispersed in the solvent (D) using a nozzle or the like while stirring the resin-containing powder particles (A).

[0157] A preferred method for completely volatilizing the solvent (D) is vacuuming. The solvent volatilization temperature is preferably 0 to 80°C. When the temperature is within the range of 0 to 80°C, a powder coating composition with a well-bonded state is easily obtained.

[0158] Furthermore, while the solvent (D) dissolves or disperses the binder (C), it does not dissolve the resin-containing powder particles (A) or the resin (A1) constituting them. Therefore, even when the solvent (D) is added, there is no concern that the resin-containing powder particles (A) will adhere to each other, increasing the particle size of the resin-containing powder particles (A), reducing coating workability, or deteriorating the appearance of the coating film.

[0159] Therefore, the powder coating composition according to the present invention can form a coating film having gloss and excellent glitter, and also has excellent recyclability.

[0160] In the powder coating composition according to the present invention, a specific virtual resin X is set as a resin applicable to the plurality of resins (A1) constituting the resin-containing powder particles (A), and a specific center coordinate CC (δ d , δ p , δ h ) = (19.0, 7.0, 5.0). Therefore, when the solvent (D) present outside the specific Hansen dissolve spheres is used as a solvent for the binder (C), the binder (C) can be dissolved or dispersed without dissolving the various resins (A1) present inside the Hansen dissolve spheres. Therefore, in the present invention, it is possible to bind the luster pigment to various resin-containing powder particles.

[0161] (Effect)

[0162] According to the powder coating composition of the present invention, it is possible to provide a powder coating composition that can form a coating film having high glitter and gloss and has excellent recyclability.

[0163] [Coating]

[0164] The coating film of the present invention is formed using the powder coating composition of the present invention. Examples of methods for forming the coating film include electrostatic powder coating, corona charging, and triboelectric charging powder coating.

[0165] The thickness of the coating film is not particularly limited, but is preferably 20 to 1000 μm, more preferably 20 to 500 μm, and even more preferably 20 to 300 μm. When the coating film is applied to components for high-rise buildings, such as aluminum curtain walls, the thickness is preferably 20 to 90 μm. When the coating film is applied to components requiring high weather resistance, such as outdoor air conditioner units, signal poles, and signs installed along coastal areas, the thickness is preferably 100 to 200 μm.

[0166] The method for forming the coating film is not particularly limited. For example, the following method can be used: applying the powder coating composition of the present invention to a substrate to form a molten film composed of a melt of the powder coating composition, and then cooling the molten film to form a coating film.

[0167] The molten film composed of the melt of the powder coating composition can be obtained, for example, by forming the film while applying the powder coating composition to a substrate or by forming the film by heating and melting the powder coating composition on the substrate after the powder coating composition is attached to the substrate.

[0168] Furthermore, when the powder coating composition contains a curing agent, the curing reaction of the reactive components in the composition may begin approximately simultaneously with the heating and melting of the powder coating composition. In this case, the coating film formation method is preferably a method in which the heating and melting of the powder coating composition and the adhesion to the substrate are performed approximately simultaneously, or a method in which the powder coating composition is adhered to the substrate and then heated and melted.

[0169] The heating and melting of the powder coating composition, as well as the heating temperature (hereinafter also referred to as the "baking temperature") and the heating maintenance time (hereinafter also referred to as the "baking time") for maintaining the heated and molten state for a predetermined time are appropriately set depending on the types and composition of the raw material components of the powder coating composition, the desired coating film thickness, etc.

[0170] When the powder coating composition does not contain a curing agent, the baking temperature is preferably 160-300°C. When the powder coating composition contains a curing agent, the baking temperature is preferably set according to the reaction temperature of the curing agent. When a curing agent is used, the baking temperature is preferably 120-240°C.

[0171] The reaction temperature of the curing agent is determined by measuring the change in elastic modulus of the powder coating composition. The change in elastic modulus can be measured using a rheometer such as ARES Rheometer manufactured by TA Instruments, Inc., Japan.

[0172] The baking time is preferably 2 to 60 minutes. When the powder coating composition does not contain a curing agent, the baking time is more preferably 5 to 60 minutes, and even more preferably 10 to 50 minutes. When the powder coating composition contains a curing agent, the baking time is more preferably 2 to 50 minutes, and even more preferably 5 to 40 minutes.

[0173] As the coating method used in the formation method of the coating film, electrostatic coating, electrostatic spraying, electrostatic dipping, spraying, flow dipping, spraying, spraying, spraying, plasma spraying, etc. can be used. Wherein, from the excellent aspect of the surface smoothness of the molten film, the electrostatic coating method of the powder coating gun is preferably utilized. As the powder coating gun, corona charging type coating gun, friction charging type coating gun, etc. can be used. Here, the corona charging type coating gun refers to a gun that is subjected to corona discharge treatment and sprayed by the powder coating composition. In addition, the friction charging type coating gun refers to a gun that is subjected to friction charging treatment and sprayed by the powder coating composition.

[0174] The cooling temperature of the molten film is preferably 20-25°C. When the powder coating composition of the present invention contains a curing agent, the resulting coating film becomes a cured film. Cooling after baking can be either rapid or gradual cooling, with gradual cooling being preferred to prevent the coating film from peeling off the substrate.

[0175] (Effect)

[0176] According to the coating film of the present invention, it is possible to form a coating film having high glitter and gloss using a powder coating composition that is excellent in recyclability.

[0177] [Coating body]

[0178] The coated body according to the present invention comprises: a substrate; and a coating film formed on the surface of the substrate using the powder coating composition according to the present invention.

[0179] (Base material)

[0180] As the substrate, for example, a substrate made of metal (iron, stainless steel, aluminum, copper, titanium, brass, aluminum alloy, etc.), steel, cast iron, etc. can be preferably used. As the steel, alloy steel, special steel, and carbon steel can be used.

[0181] Specific examples of the substrate composed of aluminum alloy include building window frames, building panels, etc. Specific examples of the substrate composed of carbon steel include railway bridges, highway bridges, gas tanks, oil tanks, steel towers, springs, etc.

[0182] The coated body according to the present invention is obtained by using the powder coating composition according to the present invention and carrying out the coating film forming method described in the section "Coating Film According to the Present Invention".

[0183] (Effect)

[0184] According to the coated body of the present invention, it is possible to form a coating film having gloss and excellent glitter properties using a powder coating composition that is also excellent in recyclability.

[0185] [Example]

[0186] Hereinafter, the present invention will be described in further detail by way of examples, but the present invention is not limited to these examples. In addition, regarding the description of the examples and comparative examples, "parts" and "%" are based on mass standards.

[0187] In the Examples and Comparative Examples described below, the following raw materials were used.

[0188] <1. Raw Materials for Powder Coating Compositions>

[0189] (1) Raw materials containing resin powder particles (A)

[0190] (1-1) Binder resin (A11)

[0191] Fluororesin 1: LUMIFLON LF710F, hydroxyl-containing fluororesin (hydroxyl value: 46 mgKOH / g, manufactured by AGC Corporation)

[0192] Polyester resin 1: U-Pica Coat GV560, a hydroxyl-containing polyester resin (hydroxyl value: 50 mgKOH / g, acid value: 5 mgKOH / g, softening point: 125°C, manufactured by U-Pica Co., Ltd., Japan)

[0193] Polyester resin 2: CRYLCOAT 1683-0, carboxylic acid-containing polyester resin (acid value: 50 mgKOH / g, manufactured by Daicel Allnex Co., Ltd.)

[0194] Polyester resin 3: CRYLCOAT 2630-2, carboxylic acid-containing polyester resin (acid value: 33 mgKOH / g, manufactured by Daicel Allnex Co., Ltd.)

[0195] (1-2) Curing agent (A12)

[0196] Curing agent 1: ε-caprolactam blocked isocyanate (manufactured by Evonik Degussa Co., Ltd., trade name: Vestagon B1530)

[0197] Curing agent 2: Bis-A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: jER (registered trademark) 1004)

[0198] Curing agent 3: β-Hydroxyalkylamide (manufactured by EMS-CHEMIE Co., Ltd., trade name: Primid XL-552)

[0199] (1-3) Additives (A3)

[0200] Additive 1: Silica-based surface conditioner (BYK-Chemie Co., Ltd., trade name: BYK360P)

[0201] Lubricant 1: Amorphous silica (manufactured by Fuji Silysia Co., Ltd., trade name: SYLYSIA 358)

[0202] (2) Glitter paint (B)

[0203] ·Aluminum sheet 1: PCF7620A (manufactured by Toyo Aluminum Co., Ltd.)

[0204] (3) Binder (C)

[0205] Binder 1: Joncryl JDX-C3000 (manufactured by BASF, acrylic resin, active ingredient 100% by mass, Tg 57°C, weight-average molecular weight 10,000)

[0206] Binder 2: PLUS COAT Z-730 (manufactured by Huying Chemical Industry Co., Ltd., polyester resin aqueous solution, active ingredient 25% by mass, Tg 46°C, weight-average molecular weight 3000)

[0207] Binder 3: Burnock WD-551P (manufactured by DIC Corporation, aqueous hydroxyl-containing acrylic resin dispersion, active ingredient 40% by mass, Tg 40°C, weight-average molecular weight 28,000)

[0208] Binder 4: WATERSOL EFD-5580 (manufactured by DIC Corporation, aqueous acrylic resin dispersion, active ingredient 40% by mass, Tg 15°C, weight-average molecular weight 70,000)

[0209] Binder 5: JER 1001 (manufactured by Mitsubishi Chemical Corporation, epoxy resin, active ingredient 100% by mass, Tg 64°C, weight average molecular weight 3000)

[0210] Binder 6: HA 3509 (manufactured by Resonac Holdings Co., Ltd., acrylic resin solution, active ingredient 55% by mass, Tg 50°C, weight-average molecular weight 7500)

[0211] Binder 7: YS POLYSTAR TH130 (manufactured by Yasuhara Chemical Co., Ltd., terpene-phenol resin, active ingredient 100% by mass, Tg 130°C, weight-average molecular weight 1500)

[0212] (4) Solvent (D)

[0213] Solvent 1: Ion exchange water

[0214] Solvent 2: Mixture of 75 wt% ion-exchanged water and 25 wt% methanol (manufactured by Kanto Chemical Co., Ltd.)

[0215] Solvent 3: Mixture of 50 wt% ion-exchanged water and 50 wt% methanol (manufactured by Kanto Chemical Co., Ltd.)

[0216] Solvent 4: Mixture of 25 wt% ion-exchanged water and 75 wt% methanol (manufactured by Kanto Chemical Co., Ltd.)

[0217] Solvent 5: Methanol (manufactured by Kanto Chemical Co., Ltd.)

[0218] Solvent 6: Ethylene glycol (manufactured by Kanto Chemical Co., Ltd.)

[0219] Solvent 7: Xylene (manufactured by Kanto Chemical Co., Ltd.)

[0220] Solvent 8: n-heptane (manufactured by Kanto Chemical Co., Ltd.)

[0221] Solvent 9: Perfluoromethylcyclohexane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0222] Table 2 shows the ratio of the mass of the coating component after drying to the mass of the coating component before drying of the binder (C), namely, NV (%), the glass transition point Tg (° C.), and the weight average molecular weight Mw.

[0223] [Test Example 1]

[0224] The HSP (δ d , δ p , δ h ). In addition, the HSP of the solvent (D) is (δ d,2 , δ p,2 , δ h,2 ), but in the test examples and the following embodiments and comparative examples, it is simply expressed as (δ d , δ p , δ h ).

[0225] In addition, the distance (δ d , δ p , δ h ) = (19.0, 7.0, 5.0) the distance of the specific center coordinates CC is the interaction distance R a .

[0226] HSP (δ d , δ p , δ h ) and interaction distance R a Shown in Table 2.

[0227] [Table 1]

[0228]

[0229] [Table 2]

[0230]

[0231] [Test Example 2]

[0232] (Solubility evaluation test)

[0233] Binders 1, 2, and 5-7 were each reduced to 100% solids at 25°C and 760 mmHg (gauge pressure), and 0.01 g of each was weighed. Next, each of these binders 1, 2, and 5-7 was mixed with 10 ml each of solvents 1-9 and stirred at 25°C for 30 minutes. After stirring, the mixture was allowed to stand for 24 hours, and the resulting product was visually evaluated. The evaluation results are shown in Table 3. The evaluation criteria are as follows.

[0234] Furthermore, since binders 3 and 4 consist of a resin component dispersed in water (solvent 1), and since they form a film when the solids content reaches 100%, the original resin solubility cannot be determined. Therefore, 0.04g (solids content 0.01g) of binder 3 was weighed, and methanol was added to achieve the same water / methanol ratio as in solvents 2 and 3, and the dispersion state was evaluated. For binder 4, 0.018g (solids content 0.01g) was weighed, and methanol was added to achieve the same water / methanol ratio as in solvents 2 and 3, and the dispersion state was evaluated.

[0235] <Evaluation>

[0236] Evaluation was performed as follows.

[0237] ◎ (Excellent): Transparent liquid, soluble.

[0238] ○ (good): turbid liquid, in a dispersed state (no precipitation).

[0239] × (poor): A state where a precipitate starts to form during stirring.

[0240] -: Decentralized evaluation has not been implemented.

[0241] [Table 3]

[0242]

[0243] [Examples 1 to 36, Comparative Examples 1 to 15]

[0244] (1. Preparation of Powder Coating Composition)

[0245] <1-1: Preparation of Resin-Containing Powder Particles (A)>

[0246] (1) 1-1-1: Preparation of powder particles containing fluororesin and polyester resin

[0247] The raw materials listed in Tables 1 and 2 were mixed in the proportions shown in Tables 4 and 5 to produce powder particles (A) containing a fluororesin and a polyester resin. Specifically, the fluororesin, polyester resin, curing agent (blocked isocyanate), additives, and lubricant were placed in a high-speed mixer and mixed for 1 minute. The mixture was then kneaded using a single-screw kneader (Buss) controlled at 120°C, and the ejected kneaded product was cold-rolled using chill rolls. The resulting mixture was then pulverized using a pin mill and classified using a 150-mesh screen to produce powder particles (A) (50% volume average particle size: approximately 35 μm) that served as the raw materials for the powder coating compositions (Coatings 1-17).

[0248] (2) 1-1-2: Preparation of powder particles containing polyester resin and epoxy resin

[0249] The raw materials listed in Tables 1 and 2 were mixed in the proportions shown in Tables 6 and 7 to produce powder particles (A) containing a polyester resin and an epoxy resin. Specifically, the polyester resin, epoxy resin, and additives were placed in a high-speed mixer and mixed for one minute. The mixture was then kneaded using a single-screw kneader (manufactured by BUSS Co., Ltd.) at a temperature of 120°C. The ejected kneaded product was then cold-rolled using chill rolls. The mixture was then pulverized using a pin mill, classified using a 150-mesh screen, and a lubricant was added to obtain the powder particles (A) (50% volume average particle size: approximately 35 μm) that served as the raw materials for the powder coating compositions (Coatings 18-34).

[0250] (3) 1-1-3: Preparation of powder particles containing polyester resin and amide compound

[0251] The raw materials listed in Tables 1 and 2 were mixed in the proportions shown in Tables 8 and 9 to produce powder particles (A) containing a polyester resin and an amide compound. Specifically, the polyester resin, amide compound, additives, and lubricant were placed in a high-speed mixer and mixed for 1 minute. The mixture was then kneaded using a single-screw kneader (manufactured by BUSS Co., Ltd.) at a temperature of 120°C. The ejected kneaded material was then cold-rolled using chill rolls. The mixture was then pulverized using a pin mill and classified using a 150-mesh screen to produce powder particles (A) (50% volume average particle size: approximately 35 μm) that served as the raw materials for the powder coating compositions (Coatings 35-51).

[0252] <1-2: Preparation of adhesive solution>

[0253] The binder and the binder solvent were mixed so as to have the blending ratios shown in Tables 4 to 9, thereby preparing binder liquids for producing powder coating compositions (coating materials 1 to 51).

[0254] <1-3: Preparation of Powder Coating Compositions (Coatings 1 to 51)>

[0255] To the powder particles (A) obtained by the above method, a glitter pigment (PCF7620A, manufactured by Toyo Aluminum Co., Ltd., average particle size 21 μm, resin-coated aluminum powder) was added so as to achieve the blending ratios shown in Tables 4 to 9, and the mixture was mixed with a spatula until uniform.

[0256] Next, the binder solution obtained by the above method was added and kneaded while air-drying for 1 hour. This mixture was placed in a 1L volumetric flask and, using an evaporator, rotary-mixed for 30 minutes while vacuum-drying at room temperature for 20 minutes. The resulting powder was classified using a 100μm mesh to obtain powder coating compositions (Coatings 1-51).

[0257] (2. Characteristic evaluation)

[0258] The properties of the obtained powder coating compositions (Coatings 1 to 51) were evaluated. The results of the respective evaluation tests are shown in Tables 4 to 9. In addition, in the evaluation tests of sparkle and surface smoothness, test pieces prepared as follows were used.

[0259] <2-1: Test piece preparation method>

[0260] Each powder coating was electrostatically coated on one side of a chromate-treated aluminum plate (substrate) using an electrostatic coating machine equipped with a powder coating gun (manufactured by Onoda Cement Co., Ltd., trade name: GX3600C). The coating was then maintained in a 200°C atmosphere for 20 minutes. The coating was then allowed to cool to room temperature, resulting in an aluminum plate (test piece) with a coating film (cured film) having a thickness of 55 to 65 μm.

[0261] <2-2: Evaluation>

[0262] The layer separation property, glitter property, surface smoothness and recyclability were measured and evaluated as follows.

[0263] (1) Layer separation

[0264] Cross-sections of the coating films of Examples 1 to 12 and Comparative Examples 1 to 5 were observed using a microscope (Keyence) to evaluate whether the coating films were separated into upper and lower layers. Furthermore, cross-sections of the coating films were similarly observed using a scanning electron microscope (Ultra-High Resolution Analytical Scanning Electron Microscope SU-70, Hitachi High-Technologies Corporation), and elemental analysis was performed to confirm the distribution of fluorine (fluororesin) within the coating film cross-sections.

[0265] Evaluation was performed as follows.

[0266] ○ (good): Fluorine element is concentrated on the surface of the coating film.

[0267] × (poor): No concentration of fluorine element on the coating surface was observed.

[0268] (2) Flash

[0269] Evaluation was performed as follows.

[0270] For each test piece, color unevenness of the coating film was visually evaluated according to the following criteria.

[0271] ○ (good): Color unevenness occurs in 20% or less of the entire area of ​​the test piece.

[0272] × (poor): Color unevenness occurs over more than 20% of the entire area of ​​the test piece.

[0273] (3) Surface smoothness

[0274] Evaluation was performed as follows.

[0275] The state of the coating film surface after the test plate was prepared was evaluated by visual observation.

[0276] ◎ (Excellent): No abnormalities

[0277] ○ (good): orange peel

[0278] × (bad): Rough surface

[0279] (4) Recyclability

[0280] Evaluation was performed as follows.

[0281] The coating material not applied in the first coating was re-coated, and the color unevenness of the coating film was visually evaluated according to the following criteria for each test piece.

[0282] ○ (good): Color unevenness occurs in 20% or less of the entire area of ​​the test piece.

[0283] × (poor): Color unevenness occurs over more than 20% of the entire area of ​​the test piece.

[0284] The results are shown in Tables 4 to 9.

[0285] [Table 4]

[0286]

[0287] [Table 5]

[0288]

[0289] [Table 6]

[0290]

[0291] [Table 7]

[0292]

[0293] [Table 8]

[0294]

[0295] [Table 9]

[0296]

[0297] According to the Examples and Comparative Examples, it can be seen that the powder coating compositions of the Examples have good glitter, surface smoothness, and recyclability.

[0298] Description of Reference Numerals

[0299] CC center coordinates

[0300] G Hansen's 3D chart

[0301] HSS Hansen's Dissolving Sphere

[0302] R0 interaction radius

[0303] R a interaction distance

Claims

1. A powder coating composition comprising resin-containing powder particles (A), a glitter pigment (B), and a binder (C), wherein the powder coating composition is characterized in that: The binder (C) is dissolved or dispersed in the Hansen dissolving sphere whose central coordinate (δ d , δ p , δ h ) is set to (19.0, 7.0, 5.0) a A resin having a Tg of 30° C. or higher and a weight average molecular weight of 1,000 to 100,000 in a solvent (D) of 20 or higher.

2. The powder coating composition according to claim 1, characterized in that The binder (C) is dissolved or dispersed in the interaction distance R a The resin in the solvent (D) is 30 or more.

3. The powder coating composition according to claim 1, characterized in that The Tg of the binder (C) is 40° C. or higher.

4. The powder coating composition according to claim 1, characterized in that The resin (A1) constituting the resin-containing powder particles (A) is obtained by reacting one or more binder resins (A11) selected from the group consisting of fluororesins, polyester resins, and acrylic resins, and one or more curing agents (A12) selected from the group consisting of compounds having an epoxy group or polymers thereof, amide compounds, and isocyanate compounds.

5. The powder coating composition according to claim 1, characterized in that The solvent (D) is one or more solvents selected from the group consisting of water, ethylene glycol, and methanol.

6. The powder coating composition according to claim 1, characterized in that The solvent (D) is a mixed solvent of water and a water-soluble organic solvent.

7. The powder coating composition according to claim 1, characterized in that The glitter pigment (B) is a flaky aluminum sheet. 8 . A coating film formed using the powder coating composition according to claim 1 .

9. A coated body comprising: substrate; and A coating film formed on the surface of the substrate using the powder coating composition according to any one of claims 1 to 7.

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